Fuel cells are electrochemical devices that produce usable electricity by the catalyzed combination of a fuel such as hydrogen and an oxidant such as oxygen. In contrast to conventional power plants, such as internal combustion generators, fuel cells do not utilize combustion. As such, fuel cells produce little hazardous effluent. Fuel cells convert hydrogen fuel and oxygen directly into electricity, and can be operated at higher efficiencies compared to internal combustion generators.
A fuel cell such as a proton exchange membrane (PEM) fuel cell typically contains a membrane electrode assembly (MEA), formed by an electrolyte membrane disposed between a pair of catalyst layers, which are correspondingly disposed between a pair of gas diffusion layers. The respective sides of the electrolyte membrane are referred to as an anode portion and a cathode portion. In a typical PEM fuel cell, hydrogen fuel is introduced into the anode portion, where the hydrogen reacts and separates into protons and electrons. The electrolyte membrane transports the protons to the cathode portion, while allowing a current of electrons to flow through an external circuit to the cathode portion to provide power. Oxygen is introduced into the cathode portion and reacts with the protons and electrons to form water and heat.
A common obstacle in the commercial application of PEM fuel cells is the performance of the catalyst layers. Despite its cost, platinum is currently the material of choice for catalyst layers. However, to achieve desirable operation voltages, large amounts of platinum are required for the catalyst layers, which increases material costs. Additionally, at high voltages, platinum may react with water and/or oxygen, thereby producing an oxide layer that inhibits its catalytic activity in the oxygen reduction reaction. As such, there is a need for alternative catalyst materials, and methods of making catalyst layers from such materials, that provide advantages in terms of cost, performance, and durability.